Motion controlling hinge for orthopedic brace

ABSTRACT

A motion controlling hinge for an orthopedic brace is provided. The hinge includes an actuator secured to one arm, and at least one spring member. As the arm with the actuator pivots in a first direction, at a predetermined flexion angle the actuator applies a force to the spring member, causing the spring member to flex. The spring member exerts a force on the actuator tending to bias the actuator away from the spring member, and tending to bias the arm in a second direction opposite the first direction. In a preferred embodiment, the spring member comprises a plurality of flat bar leaf springs. A movable fulcrum enables adjustment of a force exerted by the spring member on the actuator. A variety of differently sized adapters are securable to the actuator. The size of the adapter determines the flexion angle at which the spring member first exerts force on the actuator.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/355,486, filed Jan. 30, 2003, currently pending, the entirety ofwhich is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to orthopedic bracing. More particularly,the present motion controlling hinge for an orthopedic brace providesresistance to joint extension, with the resistance beginning at apredetermined angle and increasing as the joint extends further.

2. Description of the Related Art

The quadriceps muscles serve as an anterior cruciate ligament (ACL)antagonist that strain the ACL, particularly at smaller knee flexionangles. At knee flexion angles less than 60°, a component of thequadriceps force acts in the anterior direction. Knee structures,primarily the ACL, resist this anterior component. Thus, quadricepscontractions at small flexion angles place strain on the ACL. Thisstrain may be responsible for many ACL injuries. For patients who haverecently undergone ACL reconstruction, this strain can cause permanentstretching of the ACL graft, which can in turn create knee instabilitythat could lead to injury of other structures (e.g. meniscus), or todegenerative changes within the joint. In some cases, the patient mustundergo a second invasive procedure to reduce the instability.

Because of the risk of ACL damage at small flexion angles, physicianscommonly recommend avoiding quadriceps contractions at small flexionangles. However, people often have difficulty avoiding small flexionangles during normal activities. Furthermore, movement and activity areimportant to promoting healing and reducing detrimental effects of ACLreconstruction. Therefore, a knee brace that allows patients to avoidquadriceps contractions at small flexion angles would be of greatbenefit to ACL reconstruction patients or to people who suffer from ACLdeficiencies.

One type of knee brace that allows patients to avoid small flexionangles is a brace having extension stops, such that the wearer cannotextend his or her knee past a particular flexion angle. For example,U.S. Pat. No. 4,732,143 to Kausek et al. provides an extension stopremovably mountable on a polycentric hinge. The stop limits the forwardpivotal rotation of a pair of rigid arms pivotally connected by thehinge. The hinge includes a pair of rigid arms connected at spaced-apartpivotal connections between a pair of parallel face plates. Intermeshinggear teeth on the mating ends of the arms cause simultaneous pivotalaction of both arms about their pivotal connections with the plates. Theextension stop is a C-shaped plastic body that is attachable along oneof the face plates. The stop includes a resilient clip for attaching thestop to one of the face plates. The stop further includes an extensionblock positionable between the mating ends of the arms to limit theforward rotation of the arms. The extension stop is made of a strong,lightweight plastic. Differently sized block means are provided to allowthe user to select the limit of extension.

A brace such as the one described in Kausek et al. halts the wearer'sknee extension at a particular flexion angle. A patient wearing such abrace experiences a jarring at maximum extension as the brace comes to asudden halt. Many patients may find this jarring uncomfortable, and thejarring may cause many patients to fail to comply with therehabilitation guidelines set by their physicians. A joint brace thatprovides a cushioned stop at full joint extension and/or full jointflexion can help to reduce or eliminate uncomfortable jarring. The bracemight make patients feel safer and more confident, which may lead tobetter patient compliance with rehabilitation programs and speedierrecovery times.

Athletes frequently leap off of the ground during various athleticactivities. These athletes preferably land with their knees slightlybent. The impact causes their knees to bend further as the quadricepsmuscles contract to provide a force that decelerates and eventuallyhalts knee flexion. The knees thus absorb the impact forces and preventthese forces from damaging fragile bones and other joints.

Occasionally, however, athletes do not flex their knees while they arein the air. Studies have shown that female athletes tend not to flextheir knees as much as male athletes do when landing after a jump. Whena person lands with his or her knees fully extended, the knees do notbend. Instead, all of the impact forces are absorbed by the athlete'sbones and/or joints. Such jarring impacts frequently cause injuries. Ifan athlete were to wear knee braces that included a stop or a cushionthat prevented full knee extension, or that biased the knee joint awayfrom full extension, the braces would force the athlete to flex his orher knees while airborne. The athlete would thus always land on flexedknees and would be less likely to injure himself or herself.

Several joint braces include hinges that either prevent full jointextension, or provide a cushioned stop at full joint extension. U.S.Pat. No. RE37,209 to Hensley et al. provides an extension decelerationorthosis. The orthosis performs the function of those ligaments thatcontrol joint motion, and provides added anteroposterior jointstability. The orthosis comprises a lightweight, external springassembly, upper and lower elongated arms, and a centric or polycentricfulcrum. The orthosis is adjustable for its range of motion, adaptablefor use on many different style orthoses, and includes variable strengthto suit corrective, preventive, anthropomorphic, environmental, andusage requirements. The orthosis includes means for mechanicallydampening a limb's angular velocity on extension to preventhyperextension. The orthosis further includes means for accelerating thelimb's angular velocity on flexion to enable quicker, smoother, lessstressful motion. In one embodiment, spring rods are assembled mediallyand laterally to conventional pairs of elongated orthotic brace arms.The spring rods span the joint fulcrum point by serpentinely engagingroller posts. The assemblage thus decelerates the limb during the last15 to 20 degrees of extension, preventing the arms from striking a stop,which would create a risk of hyperextension. The assemblage also usesthe stored energy of the spring to facilitate limb flexion.

U.S. Pat. No. 6,074,355 to Bartlett provides a knee brace having threepoint fixation and including a pair of first arm members positioned onopposite sides of the knee joint. The lower leg brace member has a pairof second arm members oriented and positionable on opposite sides of theknee joint. The rigid thigh member and lower leg member are secured tothe wearer's leg by means of a flexible strap extending around the backof the leg and adjustably attached thereto. The mating ends of the armsare connected by a pair of parallel spaced-apart face plates formingpolycentric hinges that permit the mating ends of the arms to pivotabout the connections. Various forms of extension cushions are providedto limit the proximity of the mating ends to one another to therebylimit the forward movement of the arms.

None of these braces provides the ability to adjust a magnitude of aforce that restrains hinge motion without the necessity of interchanginghinge parts. Further none of these braces provides the advantageouscombination of easy adjustability of a magnitude of a force thatrestrains hinge motion, and easy adjustability of an angle at which thehinge motion controlling force is applied. Therefore, a hinge for anorthopedic brace that provided these advantages would be of greatbenefit to wearers of orthopedic braces.

SUMMARY OF THE INVENTION

The preferred embodiments of the motion controlling hinge for orthopedicbrace have several features, no single one of which is solelyresponsible for their desirable attributes. Without limiting the scopeof this invention as expressed by the claims that follow, its moreprominent features will now be discussed briefly. After considering thisdiscussion, and particularly after reading the section entitled“Detailed Description of the Preferred Embodiments,” one will understandhow the features of the preferred embodiments provide advantages, whichinclude easy adjustability of a magnitude of a force that restrainshinge motion, and easy adjustability of an angle at which the hingemotion controlling force is applied.

A preferred embodiment of the hinge for orthopedic brace comprises ahinge plate, a spring member, and first and second arms pivotablysecured to the hinge plate. An actuator is secured to the second arm. Asthe arms pivot in a first direction such that an angle between themincreases, once the arms reach a desired extension angle, the springmember exerts a force on the actuator tending to bias the second arm ina second direction opposite the first direction.

Another preferred embodiment of the hinge for orthopedic brace comprisesan orthopedic brace including a hinge. The hinge comprises a hingeplate, a spring member and first and second arms pivotably secured tothe hinge plate. An actuator is secured to the second arm. As the bracepivots toward full extension, the spring member exerts a force on theactuator tending to bias the brace away from full extension.

Another preferred embodiment of the hinge for orthopedic brace comprisesa hinge plate, a leaf spring, and first and second arms pivotablysecured to the hinge plate. An actuator is secured to the second arm. Asthe second arm pivots in a first direction, the actuator contacts theleaf spring, causing the leaf spring to flex such that the leaf springexerts a force on the actuator tending to bias the actuator away fromthe leaf spring, and tending to bias the second arm in a seconddirection opposite the first direction.

Another preferred embodiment of the hinge for orthopedic brace comprisesa hinge plate, a leaf spring shaped substantially as a flat bar, andfirst and second arms pivotably secured to the hinge plate. As the armspivot toward a first configuration in which an angle between themapproaches 180°, the leaf spring exerts a force on the second armtending to bias the second arm away from the first configuration.

Another preferred embodiment of the hinge for orthopedic brace comprisesa resistance member for providing resistance to motion of the hinge in afirst direction within a predetermined range of motion of the hinge, andan adjustment member adapted to apply a force on the resistance memberfor adjusting an amount of the resistance provided by the resistancemember. When the adjustment member is located in a first locationrelative to the resistance member, the resistance provided by theresistance member has a first magnitude. When the adjustment member islocated in a second location relative to the resistance member, theresistance provided by the resistance member has a second magnitude thatis different from the first magnitude.

BRIEF DESCRIPTION OF THE DRAWINGS

The preferred embodiments of the motion controlling hinge for orthopedicbrace, illustrating its features, will now be discussed in detail. Theseembodiments depict the novel and non-obvious hinge shown in theaccompanying drawings, which are for illustrative purposes only. Thesedrawings include the following figures, in which like numerals indicatelike parts:

FIG. 1 is a top-rear perspective view of a preferred embodiment of themotion controlling hinge for orthopedic brace according to the presentinvention;

FIG. 2 is a bottom-rear perspective view of the hinge of FIG. 1;

FIG. 3 is an exploded top-rear perspective view of the hinge of FIG. 1;

FIG. 4 is a partially exploded top-rear perspective view of theactuator, adapter, bumper, springs, fulcrum, arms and outer hinge plateof the hinge of FIG. 1;

FIG. 5 is a top plan view of the actuator, adapter, bumper, springs,fulcrum, arms and friction plate of the hinge of FIG. 1, illustratingthe configuration of these components when the arms are positioned suchthat the adapter contacts the bumper and the springs are undeflected;

FIG. 6 is a top plan view of the springs of the hinge of FIG. 1,illustrating, schematically, the bending load applied to the springs bythe hinge components;

FIG. 7 is a top plan view of the components of FIG. 5, illustrating theconfiguration of these components when the arms are positioned at fullextension, such that the springs are fully deflected, and the fulcrum islocated at a maximum distance from the bumper;

FIG. 8 is a top plan view of the components of FIG. 5, illustrating theconfiguration of these components when the arms are positioned at fullextension, such that the springs are fully deflected, and the fulcrum islocated at a minimum distance from the bumper;

FIG. 9 is a bottom-rear perspective view of the actuator, adapter,bumper, springs and outer hinge plate of the hinge of FIG. 1;

FIG. 10 is a bottom plan view of the actuator, adapter, bumper, springs,fulcrum and outer hinge plate of the hinge of FIG. 1, illustrating theconfiguration of these components when the arms are positioned such thatthe adapter contacts the bumper and the springs are undeflected;

FIG. 11 is a bottom plan view of the actuator, adapter, bumper, springs,fulcrum and outer hinge plate of the hinge of FIG. 1, illustrating theconfiguration of these components when the arms are positioned at fullextension, such that the springs are fully deflected, and the fulcrum islocated at a maximum distance from the bumper;

FIGS. 12-14 are top plan views of the actuator, adapter, bumper,springs, fulcrum, arms and friction plate of the hinge of FIG. 1,illustrating adapters of different sizes, and the relativeconfigurations of these components when the arms are positioned suchthat the adapter contacts the bumper and the springs are undeflected;

FIG. 15 is a top plan view of the hinge of FIG. 1, illustrating the easyaccessibility of the adapter with the cosmetic cover removed; and

FIG. 16 is a top-rear perspective view of the actuator, adapter, bumper,springs and arms of the hinge of FIG. 1, illustrating the screw that ispreferably used to hold the adapter in place on the second arm.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 and 2 illustrate the exterior of the present motion controllinghinge 20 for orthopedic brace. FIG. 3 illustrates, in an exploded view,the interior components of the hinge 20. The hinge 20 comprises a firstrigid arm 22 and a second rigid arm 24 pivotably secured between aninner hinge plate 26 (FIGS. 2 and 3) and an outer hinge plate 28 (FIGS.1 and 3). With reference to FIGS. 3 and 4, each hinge plate 26, 28preferably includes a first pivot aperture 30 and a second pivotaperture 32 spaced from the first pivot aperture 30. Each arm 22, 24preferably includes a pivot aperture 34 near a mating end thereof. Asshown in FIGS. 2 and 3, a first fastening member 36, such as a rivet,passes through the first pivot aperture 30 on each hinge plate 26, 28and through the pivot aperture 34 on the first arm 22, thereby pivotablysecuring the first arm 22 between the hinge plates 26, 28. A secondfastening member 36, such as a rivet, passes through the second pivotaperture 32 on each hinge plate 26, 28 and through the pivot aperture 34on the second arm 24, thereby pivotably securing the second arm 24between the hinge plates 26, 28.

In the illustrated embodiment, the pivot aperture 34 on each armcontains a reinforcing insert 38 (FIG. 4). Preferably, the arms 22, 24are constructed of a relatively inexpensive and lightweight metal, suchas aluminum. Such a lightweight metal lowers the overall weight of abrace including the present hinge 20, making the brace more comfortablefor the wearer. However, lightweight metals typically do not havesufficient hardness to enable the arms 22, 24 to withstand prolonged usein the present hinge 20. At the pivot apertures 34 in the arms 22, 24,the arms 22, 24 rub against the fastening members 36. Similarly, a firstgear tooth 40 (FIG. 4) on each arm 22, 24 rubs against gear teeth on theopposite arm 22, 24. Friction at these contact points tends to wear downthe material at the pivot apertures 34 and the first gear teeth 40.Therefore, the reinforcing inserts 38 provide the arms 22, 24 withgreater hardness at the points where the arms 22, 24 experience thegreatest wear and tear. Those of skill in the art will appreciate thatthe reinforcing inserts 38 are not necessary to achieve the advantagesof the present hinge 20. The reinforcing inserts 38 merely prolong theexpected life span of the present hinge 20 while maintaining low weightand low cost.

With reference to FIG. 16, the inserts 38 include a ring-shaped portion42 with an elongate radial protrusion 44. Opposite the radial protrusion44, the ring-shaped portion 42 includes first and second arcuateprotrusions 46 that are substantially tangential to the ring-shapedportion 42. The mating end of each arm 22, 24 preferably includes acut-out portion having a shape complementary to that of the inserts 38.The inserts 38 may be retained within the cut-out portions by anyappropriate means, such as a friction fit or an adhesive. An end of theradial protrusion 44 opposite the ring-shaped portion 44 comprises afirst gear tooth 40. The operation of the geared ends of the arms 22, 24is described in detail below. The inserts 38 are preferably constructedof a material having a high hardness, such as stainless steel. Theinserts 38 thus are better able to withstand the wear and tear that thesofter arms 22, 24 experience at the pivot apertures 34 and the firstgear tooth 40.

The hinge 20 may include a first friction-reducing plate 46 (FIG. 3)sandwiched between the outer hinge plate 28 and the arms 22, 24. Thehinge 20 may also include a second friction-reducing plate 48 sandwichedbetween the inner hinge plate 26 and the arms 22, 24. Thefriction-reducing plates 46, 48 are preferably constructed of alow-friction material, such as a plastic, TEFLON® or DELRIN®. Thefriction-reducing plates 46, 48 enable the arms 22, 24 to pivot moreeasily with respect to the hinge plates 26, 28. Those of skill in theart will appreciate that the hinge 20 need not include thefriction-reducing plates 46, 48.

An outer surface 50 of the outer hinge plate 28 preferably includes aremovable cosmetic cover 52 (FIGS. 1 and 3) that enhances the outwardappearance of the hinge 20. The cover 52 may be secured to the outerhinge plate 28 with, for example, adhesive or an interlocking “snap-fit”engagement. The cover 52 hides from view the pivot apertures 30, 32 andan adapter access opening 54, which is described in detail below.

As shown in FIGS. 3 and 4, an outer surface 56 of the second arm 24preferably includes an actuator 58 adjacent the pivot aperture 34. Inthe illustrated embodiment, the actuator 58 comprises an irregularlyshaped solid. The actuator 58 includes first and second through-holes 60(FIG. 4). The first and second through-holes 60 on the actuator 58 alignwith first and second through-holes 62 (FIG. 3) in the second arm 24.Fastening members 64 (FIG. 3), such as screws or rivets, cooperate withthe first and second through-holes 62 in the second arm 24, and with thefirst and second through-holes 60 in the actuator 58, to secure theactuator 58 to the second arm 24. Those of skill in the art willappreciate that the actuator 58 need not be secured to the second arm 24with fastening members. For example, the actuator 58 could be bonded tothe second arm 24 with adhesive, or it could be welded to the second arm24. Alternatively, the actuator 58 could be formed integrally with thesecond arm 24, such as by die-casting. If the actuator 58 is secured tothe second arm 24 with fastening members 64, as shown, preferably theinner hinge plate 26 includes a cut-out portion 112 (FIG. 2) so thatheads of the fastening members 64 do not interfere with the inner hingeplate 26.

The actuator 58 is preferably constructed of a hard durable material,such as a metal. A preferred metal is stainless steel. An adapter 66 isselectively securable to the actuator 58, as shown in FIGS. 4, 5 and 16.The adapter 66 is substantially J-shaped in top plan aspect (FIG. 5),and includes an interior curved surface 68 that is complementary to anouter side portion 70 of the actuator 58. The adapter 66 thus fitssnugly around the actuator 58. The hooked portion 72 of the adapter 66includes a crescent-shaped flange having a semi-cylindrical concave edge74. A retaining member 76, such as a screw, engages a third aperture 78(FIG. 3) in the second arm 24, such that a longitudinal axis of theretaining member 76 is substantially coextensive with a longitudinalaxis of the flange concave edge 74. A cylindrical exterior of theretaining member 76 thus cooperates with the concave edge 74 of theflange, thereby firmly holding the adapter 66 in place on the actuator58.

The adapter 66 is preferably constructed of a hard durable material,such as a metal. A preferred metal is stainless steel. As describedbelow, the adapter 66 enables easy adjustment of a joint flexion angleat which resistance to further flexion begins.

An interior of the outer hinge plate 28 (FIG. 9) houses a plurality ofleaf springs 80. In the illustrated embodiment, each leaf spring 80comprises a flat bar of resilient material. Those of skill in the artwill appreciate that the leaf springs 80 need not be shaped as flatbars. For example, the leaf springs 80 could be wedge-shaped (straighttapered bars), or the leaf springs 80 could be arcuate. An upper edge 81(FIG. 4) of each leaf spring 80 includes a ridge 83 near a first end 82thereof. A portion (not shown) of the outer hinge plate 28 has a shapethat is complementary to the shape of the ridges 83. The ridges 83 nestwithin this portion of the outer hinge plate 28, and prevent the leafsprings 80 from translating along an axis A (FIGS. 9 and 10) upon whichboth hinge plate pivot apertures 30, 32 lie.

The leaf springs 80 are preferably constructed of a resilient materialthat returns to its original shape after the removal of an applied load.A preferred material for the leaf springs 80 is stainless steel.However, those of skill in the art will appreciate that the leaf springs80 could be constructed of other materials in order to alter thestiffness of the leaf springs 80. For example, less rigid metals orplastics could be used to provide more flexible leaf springs 80, andmore rigid metals could be used to provide more stiff leaf springs 80.

In the illustrated embodiment, three leaf springs 80 are provided, andthe leaf springs 80 are freely slidable with respect to one anotherexcept in the vicinity of the ridges 83. In this vicinity, the nestingof the ridges 83 within the outer hinge plate 28 prevents the leafsprings 80 from sliding with respect to one another. The illustratedleaf springs 80 are of unequal lengths. The innermost leaf spring 80(the leaf spring 80 that lies closest to the pivot apertures 30, 32) isthe longest, and the outermost leaf spring 80 the shortest. Thisconfiguration allows the springs 80 greater freedom to flex withoutinterfering with the walls of the outer hinge plate 28. Those of skillin the art will appreciate that the leaf springs 80 need not haveunequal lengths.

The three leaf spring configuration provides the advantageouscombination of a high amount of extension resistance without significantrisk that the leaf springs 80 will break. If the three leaf springs 80are replaced by a single solid leaf spring 80 having the same stiffnessas the three illustrated leaf springs 80, the single leaf spring 80 willbe much more likely to break. Nevertheless, those of skill in the artwill appreciate that the three leaf springs 80 could be replaced by moreor fewer leaf springs 80, including a single leaf spring 80, in order tosuit a particular application. Those of skill in the art will alsoappreciate that the shape, dimensions and/or composition of each leafspring 80 could be varied to provide desired extension resistancecharacteristics for the hinge 20. For example, if greater extensionresistance is desired, some or all of the leaf springs 80 could be madeof a stiffer material. Alternatively, one leaf spring 80 having the samethickness as the three combined leaf springs 80 could be provided.Alternatively, the three springs could be adhered to one another so thatthey behave essentially as a unitary leaf spring 80.

With reference to FIGS. 9 and 10, the first end 82 of each leaf spring80 is constrained by a first wall 84 of the outer hinge plate 28 againsttranslation toward the axis A. A second wall 86 of the outer hinge plate28 constrains each leaf spring 80, at a point adjacent the first end 82of each, against translation away from the axis A. Second ends 88 of theleaf springs 80 are free to translate away from the axis A. The leafsprings 80 are thus analogous to cantilevered beams.

The outer hinge plate 28 houses a bumper 90, which is substantiallyL-shaped in plan aspect (FIG. 10). The bumper 90 is preferablyconstructed of a deformable but resilient material that provides somecushioning. Preferred materials for the bumper 90 include urethane,rubber and plastic. The bumper 90 provides a cushion between the adapter66 and the leaf springs 80, which reduces any sound made when theadapter 66 contacts the leaf springs 80, as described below. Those ofskill in the art will appreciate that the bumper 90 is not necessary toachieve the advantages of the present hinge 20. The adapter 66 maycontact the leaf springs 80 directly. Alternatively, if the adapter 66were removed completely, the actuator 58 may contact the leaf springs 80directly.

An upright portion 92 of the bumper 90 includes a flat indentation 94adjacent an interior corner where the upright portion 92 meets the baseportion 96 of the bumper 90. The flat indentation 94 receives a post 98(FIG. 9) that protrudes from the outer hinge plate 28. The post 98retains the bumper 90 in its rest position, and guides the bumper 90back to the rest position, as described below.

The outer hinge plate 28 includes a plurality of apertures 100 adjacenta front edge 102 thereof. In the illustrated embodiment, three apertures100 are provided, and all the apertures 100 include internal threads.Those of skill in the art will appreciate that more or fewer apertures100 could be provided to suit a particular application, and that theapertures 100 need not be threaded. A longitudinal axis of each apertureis substantially perpendicular to a plane defined by the outer hingeplate 28. When viewed in plan aspect (FIG. 15), centers of the apertures100 are collinear.

The apertures 100 are adapted to receive a fulcrum 104, which in theillustrated embodiment comprises a shaft with an externally threadedhead portion (FIG. 3). The head portion preferably includes a surfacefeature 106, such as a hexagonal depression, that is adapted to engagean adjustment tool, such as a hex key. The threaded portion of thefulcrum 104 engages the threads in one of the apertures 100 to securethe fulcrum 104 within that aperture, as shown in FIGS. 1 and 15. Thus,the fulcrum 104 is selectively positionable within one of the threeapertures 100. When the fulcrum 104 is disposed in one of the apertures100, the non-threaded portion of the shaft abuts the outermost leafspring 80, as shown in FIG. 4. The position of the fulcrum 104 thusdetermines the bending characteristics of the leaf springs 80, asdescribed below.

Those of skill in the art will appreciate that the fulcrum 104 could beretained within one of the apertures 100 using means other than athreaded engagement. For example, a friction fit could retain thefulcrum 104 within one of the apertures 100. However, a threadedengagement provides a wearer of a brace including the present hinge 20with the advantageous ability to quickly remove the fulcrum 104 from afirst aperture 100 and replace it in a different aperture 100. Thus,without disassembling the hinge, and without interchanging any parts ofthe hinge 20, the wearer can adjust the bending characteristics of theleaf springs 80, and thereby adjust a magnitude of the extensionresistance felt by the wearer.

The mating end of each arm 22, 24 includes a first gear tooth 40 (FIG.4) and additional gear teeth 108 (FIG. 3). The teeth 40, 108 on thefirst arm 22 interlock with the teeth 40, 108 on the second arm 24, suchthat the arms 22, 24 cannot pivot independently. As described above, theradial protrusion 44 from each reinforcing insert 38 comprises the firstgear tooth 40 on each arm 22, 24. The harder material of the insert 38reduces the amount of wear that the first gear teeth 40 experience,increasing the life span of the present hinge 20.

As the arms 22, 24 pivot, the actuator 58 and adapter 66 move with thesecond arm 24. The arms 22, 24 are freely pivotable from a full flexionconfiguration (not shown) to a flexion angle at which the adapter 66first contacts the bumper 90 (FIG. 5). As the arms 22, 24 pivot farthertoward full extension (FIG. 7), the adapter 66 applies a force to thebumper 90, compressing the bumper 90 between the adapter 66 and the leafsprings 80. As the bumper 90 compresses, it in turn applies a force tothe leaf springs 80, flexing the leaf springs 80 a small amount.Eventually, the bumper 90 compresses enough to allow the adapter 66 tocontact the leaf springs 80, as shown in FIG. 7. The bumper 90 thusreduces any noise made when the adapter 66 contacts the leaf springs 80,because the leaf springs 80 are already flexing when the adapter 66contacts the leaf springs 80. The adapter 66 and the bumper 90 thensimultaneously apply force to the leaf springs 80, flexing the leafsprings 80 farther until they contact the wall 110 (FIGS. 9 and 10) ofthe outer hinge plate 28. In the illustrated embodiment, the hinge 20reaches full extension as the leaf springs 80 contact the wall 110.Those of skill in the art will appreciate, however, that the leafsprings 80 may contact the wall 110 at any flexion angle.

The hinge assembly 20 thus places the leaf springs 80 in a three-pointbending load, as illustrated in FIG. 6. The actuator 58/bumper 90assembly applies a load A to the free ends 88 of the leaf springs 80 ina direction away from the axis A. The outer hinge plate first wall 84(FIGS. 9 and 10) applies a load W to the fixed end 82 of the leafsprings 80 in a direction away from the axis A. The outer hinge platesecond wall 86 or fulcrum 104 applies a load F to an intermediateportion of the leaf springs 80 in a direction toward the axis A. Thelocation of the load F depends upon the position of the fulcrum 104, ifthe fulcrum 104 is inserted in one of the apertures 100. If the fulcrum104 is absent, the outer hinge plate second wall 86 applies the force F.

The leaf springs 80 deflect as shown in FIG. 7 under the bending load.As the leaf springs 80 deflect from the configuration of FIG. 5 to thatof FIG. 7, the force necessary to deflect the springs an incrementalamount increases. Thus, a person wearing a knee brace including thehinge 20 experiences a steadily increasing resistive force as he or sheextends his or her knee farther and farther. The hinge 20 thus providesa cushioned stop at full extension, and eliminates the uncomfortablejarring that could cause the problems outlined above.

When the wearer relaxes his or her leg, the leaf springs 80 urge theknee to flex until the leaf springs 80 return to their straightconfiguration, which is shown in FIGS. 5 and 10. As the hinge componentsmove in this direction, the post 98 (FIG. 9) on the interior of theouter hinge plate 28 engages the base portion 96 of the bumper 90 andguides the bumper 90 back to its rest position, as shown in FIGS. 10 and11.

The multiple positions for the fulcrum 104, and the removability of thefulcrum 104, enable the wearer, or a physician treating the wearer, toquickly adjust an amount of extension resistance experienced by thewearer without disassembling the hinge and without interchanging anyparts of the hinge 20. With reference to FIG. 6, the properties of theleaf springs 80 can be determined using the well known model of a simplysupported beam with an overhanging load. The deflection at the leafspring free ends 88 is given by the following equation:

$y_{FA} = {\frac{A\left( {x - l} \right)}{6{EI}}\left\lbrack {\left( {x - l} \right)^{2} - {a\left( {{3x} - l} \right)}} \right\rbrack}$

where

y_(FA)=deflection of the leaf springs 80 at any point between theapplied load A and the reaction force F;

A=magnitude of the load applied by the actuator 58/adapter 66 to theleaf springs 80;

x=distance from the leaf spring fixed ends 82, as measured along thex-axis;

l=distance between the leaf spring fixed ends 82 and reaction force Fapplied by the hinge plate second wall 86 or fulcrum 104, as measuredalong the x-axis;

a=distance between the reaction force F applied by the hinge platesecond wall 86 or fulcrum 104 and the load A applied by the actuator58/adapter 66 to the leaf springs 80, as measured along the x-axis;

E=modulus of elasticity of the leaf springs 80 (a constant determined bythe material used to construct the leaf springs 80); and

I=moment of inertia of the leaf springs 80 (a constant determined by thecross-sectional shape of the leaf springs 80).

To determine the deflection at the leaf spring free ends 88 (which isclosely approximated by the deflection at the point of application ofthe applied load A), substitute (a+l) for x in the equation above. Theequation then simplifies to:

$y_{FA} = {\frac{- {Aa}^{2}}{3{EI}}\left( {a + l} \right)}$

This equation illustrates that the deflection at the leaf spring freeends 88 is directly dependent upon both the magnitude of the load Aapplied by the actuator 58/adapter 66 to the leaf springs 80, and thedistance a, which is the distance between the reaction force F appliedby the hinge plate second wall 86 or fulcrum 104 and the applied load A.As one of these variables decreases, the other must increase in order tomaintain a constant deflection of the leaf spring free ends 88. Thus, asthe fulcrum 104 is moved toward the leaf spring free ends 88, thusdecreasing the distance a, the applied load A must increase in order tomaintain a constant deflection. In order for a wearer of a braceincluding the hinge 20 to extend his or her knee to a givenflexion/extension angle, he or she will have to apply a greater force Aas the fulcrum 104 moves toward the leaf spring free ends 88. In otherwords, the wearer experiences increasing extension resistance as thefulcrum 104 moves toward the leaf spring free ends 88. In a preferredembodiment, the hinge 20 provides a maximum of 14 in.-lbs. of resistancewhen the fulcrum 104 is located in the aperture 100 farthest from theleaf spring free ends 88, a maximum of 28 in.-lbs. of resistance whenthe fulcrum 104 is located in the intermediate aperture 100, and amaximum of 42 in.-lbs. of resistance when the fulcrum 104 is located inthe aperture 100 closest to the leaf spring free ends 88.

With the fulcrum 104 removed (not shown), the wearer experiences verylight extension resistance. With the fulcrum 104 positioned in theaperture 100 located a maximum distance from the free ends 88 of theleaf springs 80, as illustrated in FIGS. 5 and 7, the wearer experienceslight extension resistance. With the fulcrum 104 positioned in theintermediate aperture 100, the wearer experiences an intermediate amountof extension resistance. With the fulcrum 104 positioned in the aperture100 located a minimum distance from the free ends 88 of the leaf springs80, as illustrated in FIG. 8, the wearer experiences heavy extensionresistance. Those of skill in the art will appreciate that moreapertures 100 could be provided in order to enable finer adjustment ofthe amount of extension resistance provided by the hinge 20. Those ofskill in the art will further appreciate that the fulcrum 104 could bepositionable along the leaf springs 80 using alternate apparatus. Forexample, the fulcrum 104 could comprise a portion of a switch (notshown) that is slidable along the outer hinge plate 28 and capable ofbeing locked in place at a plurality of positions along the leaf springs80.

The design of the present hinge 20 facilitates rapid removal andadjustment of the position of the fulcrum 104. As described above, thefulcrum 104 is alternately positionable in one of a plurality ofapertures 100 in the outer hinge plate 28. To secure the fulcrum 104within one of the apertures 100, the wearer inserts 38 the unthreadedshaft portion of the fulcrum 104 into one of the apertures 100 until thethreads on the fulcrum 104 engage the threads within the aperture 100.Using an adjustment tool, such as a hex key, the wearer then rotates thefulcrum 104 within the aperture 100 until the fulcrum 104 is inserted asufficient amount that it will not pop out of the aperture 100 duringnormal use of the hinge 20. Preferably, the wearer continues rotatingthe fulcrum 104 until it no longer protrudes from the outer surface 50of the outer hinge plate 28. To move the fulcrum 104 to a differentaperture 100, the wearer uses the adjustment tool to rotate the fulcrum104 in the opposite direction, so that it withdraws from the aperture100. The wearer then moves the fulcrum 104 to the desired aperture 100,and performs the insertion process just described.

The ability to quickly and easily move the fulcrum 104 from one aperture100 to another enhances the versatility of a brace including the presenthinge 20. For example, people of all different sizes and strengths maywear a brace including the present hinge 20. Wearers of great strengthwould likely benefit most from a brace having heavy extensionresistance, while those of lesser strength would likely benefit mostfrom a brace having light extension resistance. No matter the size andstrength of the wearer, however, the present hinge 20 is quickly andeasily adjustable to accommodate virtually any wearer. And theadjustment procedure does not require the wearer to disassemble thehinge or interchange any parts. Further, certain wearers may benefitfrom light extension resistance during an early phase of therapy, withthe extension resistance steadily increasing as therapy progresses.Other wearers may benefit from heavy extension resistance during anearly phase of therapy, with the extension resistance steadilydecreasing as therapy progresses. The present hinge 20 enables suchpatients to undergo a course of therapy without having to change bracesas therapy progresses.

The hinge 20 enables easy adjustment of the flexion angle at which thewearer first experiences extension resistance. As shown in FIGS. 12-14,the wearer may place adapters 66 of various sizes on the actuator 58. InFIG. 12, a relatively small adapter 66 is positioned on the actuator 58.The adapter 66 first contacts the bumper 90 at a flexion angle ofapproximately 35°, and the wearer first experiences extension resistanceat this same angle. In FIG. 13, a slightly larger adapter 66 ispositioned on the actuator 58. The adapter 66 first contacts the bumper90 at a flexion angle of approximately 45°, and the wearer firstexperiences extension resistance at this same angle. Finally, in FIG.14, an even larger adapter 66 is positioned on the actuator 58. Theadapter 66 first contacts the bumper 90 at a flexion angle ofapproximately 55°, and the wearer first experiences extension resistanceat this same angle. Those of skill in the art will appreciate thatadapters 66 of virtually any size may be positioned on the actuator 58so that the wearer first experiences extension resistance at virtuallyany flexion angle. Those of skill in the art will appreciate that theadapter 66 could be completely removed in order to further decrease theflexion angle at which the wearer first experiences extensionresistance.

As described above, the adapter 66 is secured in place with theretaining member 76 (FIGS. 15 and 16). To exchange one adapter 66 foranother of a different size, the wearer first removes the cosmetic cover52, if one is provided, from the outer hinge plate 28. The wearer canthen access the adapter 66 through the adapter access opening 54 in theouter hinge plate 28. The wearer removes the retaining member 76 usingan appropriate tool, such as a screwdriver or a hex key. The wearer canthen remove the adapter 66 from the actuator 58 using his or her fingersor a tweezers, and replace the adapter 66 with one of a different size.To secure the adapter 66 in place, the wearer replaces the retainingmember 76. Finally, the wearer replaces the cosmetic cover 52, if one isprovided.

The present hinge 20 has been described above as a hinge for providingresistance to joint extension. Those of skill in the art will appreciatethat the configuration of the present hinge 20 could easily be adaptedto enable the hinge 20 to provide resistance to joint flexion. Forexample, if the leaf springs 80 were housed within the outer hinge plate28 such that they were lay adjacent a rear edge of the outer hinge plate28, then the actuator 58/adapter 66 assembly would approach and contactthe leaf springs 80 as a flexion angle between the arms 22, 24increased.

The present hinge 20 has also primarily been described above as a hingefor use with a knee brace. Those of skill in the art will appreciatethat the present hinge 20 is adapted for use in a brace that is wornabout any body joint.

SCOPE OF THE INVENTION

The above presents a description of the best mode contemplated forcarrying out the present motion controlling hinge for orthopedic brace,and of the manner and process of making and using it, in such full,clear, concise, and exact terms as to enable any person skilled in theart to which it pertains to make and use this hinge. This hinge is,however, susceptible to modifications and alternate constructions fromthat discussed above that are fully equivalent. Consequently, this hingeis not limited to the particular embodiments disclosed. On the contrary,this hinge covers all modifications and alternate constructions comingwithin the spirit and scope of the hinge as generally expressed by thefollowing claims, which particularly point out and distinctly claim thesubject matter of the hinge.

1. A hinge for an orthopedic brace, comprising: a hinge plate; a firstarm pivotably secured to the hinge plate; a second arm pivotably securedto the hinge plate; an actuator secured to the second arm; and a springmember; wherein as the arms pivot in a flexion direction such that anangle between them decreases, once the arms reach a desired flexionangle, the spring member exerts a force on the actuator tending to biasthe second arm in an extension direction opposite the flexion direction.2. The hinge of claim 1, wherein the spring member comprises at leastone flat bar.
 3. The hinge of claim 2, wherein the spring membercomprises three flat bars.
 4. The hinge of claim 3, wherein the hingeplate supports a fixed end of the spring member, restraining the fixedend against translation along a first axis.
 5. The hinge of claim 4,wherein as the arms pivot in the flexion direction, the actuatorcontacts a free end of the spring member, flexing the spring member. 6.The hinge of claim 5, further comprising a fulcrum located intermediatethe fixed end and the free end of the spring member.
 7. The hinge ofclaim 6, wherein the fulcrum, together with the hinge plate and theactuator, creates a three-point bending load on the spring member. 8.The hinge of claim 6, wherein the fulcrum is selectively positionable ata plurality of locations along the spring member.
 9. The hinge of claim8, wherein the hinge plate includes at least one aperture.
 10. The hingeof claim 9, wherein the at least one aperture is adapted to receive thefulcrum.
 11. The hinge of claim 9, wherein the at least one apertureincludes internal threads.
 12. The hinge of claim 11, wherein thefulcrum comprises a shaft including external threads, and the externalthreads engage the internal threads in the at least one aperture tosecure the fulcrum within the aperture.
 13. The hinge of claim 1,further comprising an adapter secured to the actuator.
 14. The hinge ofclaim 13, wherein the adapter is positioned between the actuator and thespring member, such that the thickness of the adapter determines anangular position of the second arm at which the spring member firstexerts force on the actuator.
 15. The hinge of claim 14, furthercomprising a bumper positioned between the actuator and the springmember.
 16. The hinge of claim 15, wherein as the arms pivot in theflexion direction, the adapter contacts the bumper, which in turncontacts the spring member, causing the spring member to flex.
 17. Thehinge of claim 1, wherein the hinge plate is a first hinge plate, andthe hinge further comprises a second hinge plate spaced from the firsthinge plate such that the arms are located between the first and secondhinge plates.
 18. An orthopedic brace including a hinge, the hingecomprising: a hinge plate; a first arm pivotably secured to the hingeplate; a second arm pivotably secured to the hinge plate; an actuatorsecured to the second arm; and a spring member; wherein as the bracepivots toward full flexion, the spring member exerts a force on theactuator tending to bias the brace away from full flexion.
 19. A methodof adjusting a magnitude of a resistive force provided by a hinge, themethod comprising the steps of: removing a fulcrum from a first apertureof a hinge plate of the hinge; translating the fulcrum along the hingeplate to a second aperture of the hinge plate; and securing the fulcrumwithin the second aperture; wherein the hinge moves freely through apreset flexion/extension range until the hinge reaches a preset flexionangle, θ, and in a range between θ and a maximum flexion angle of thehinge, the hinge resists further flexion with a resistive force thatincreases as the hinge moves from θ to the maximum flexion angle, andwhen the fulcrum is disposed in the first aperture the resistive forceprovided by the hinge lies within a first range, and when the fulcrum isdisposed in the second aperture the resistive force provided by thehinge lies within a second range.
 20. The method of claim 19, whereinthe step of translating the fulcrum changes a position of the fulcrumrelative to at least one leaf spring associated with the hinge plate.